The present invention is generally related to a recording method and a recording apparatus, and more particularly to a recording method and a recording apparatus in which a liquid adhesion region and a liquid non-adhesion region of a surface of a material are utilized in a printing process.
One of the typical printing methods utilizing a liquid adhesion region and a liquid non-adhesion region of a surface of a material is an offset printing method. A printing apparatus using this offset printing method has a large size when a plate making process using an original plate and a printing process using a printing plate is incorporated into one apparatus. Accordingly, most of office use offset plate-making and printing apparatuses, which require compactness, are necessarily separated into a plate making apparatus and a printing apparatus.
In order to eliminate the above mentioned problem, apparatuses have been suggested in which a liquid adhesion region and a liquid non-adhesion region, which region correspond to image information, can be repeatedly formed, that is, can be reversibly operated. Examples for such apparatuses are listed in the following.
(1) water development method
Applying an electric charge on a hydrophobic photoconductive layer, exposing the layer to a light, forming a pattern including a hydrophobic part and a hydrophilic part on a surface of the photoconductive layer. Transferring onto a paper by adhering a water base developing agent on the hydrophilic part. (Japanese Patent Publication No.40-18992, Japanese Patent Publication No.40-18993, Japanese Patent Publication No.44-9512, Japanese Laid-Open Patent Application No.63-264392)
(2) a method utilizing a photochemical reaction of photochromic compounds
Causing photochromic compounds, such as spiropyran or azo dye, to be hydrophilic by photochemical reactions by irradiating an ultra-violet beam on a layer containing the photochromic compounds. ("Macromolecular thesis collection" Vol.37, No.4, p287, 1980)
(3) a method utilizing inner displacement-stress
Forming an adhesion region and a non-adhesion region for an ink on a material surface by forming amorphous and crystallized states by physical action. (Japanese Patent Publication No.54-41902)
According to the above method (1), the hydrophilic part is eliminated by discharge of electric charge after transferring a water base ink onto a paper, and thus the next printing operation can be performed. Namely, an original plate (photoconductive material) can be repeatably used. However, since this method is based on an electrophotography process, a long processing time is required such as processes for charging, exposure, development, transfer, and discharging. Thus, this method has disadvantages in miniaturization of size, reduction of cost, and realization of maintenance free operation.
According to the method (2), the hydrophobic and the hydrophilic regions can be reversely and freely controlled by selectively irradiating an ultra-violet beam or a visible beam. However, due to a low quantum efficiency, a reaction time is very long and a recording time is slow. Additionally, there is a disadvantage of low stability of the material. Therefore, this method has not reached the usable level.
According to the method (3), a recording material is stable after the recording but it is possible that a physical structure change occurs due to a temperature change. Accordingly, there is a problem related to a storage. Additionally, since erasure of the recorded pattern is performed by applying a heat pulse to the pattern and immediately cooling the corresponding area, it becomes a complex process to perform a repeated printing operation.
The inventor has conducted a research into way to eliminate the above mentioned disadvantages of the conventional apparatuses. As the results of the research, an apparatus was suggested in German Laid-Open Patent Application No. 4010275 in which apparatus formation of a latent image and a visible image on the recording material, transfer of the visible image to a plain paper, and an erasure of the latent image are easily and repeatedly performed. The suggested apparatus can perform repeated printing of the same image as well as consecutive printing of different images.
The above mentioned apparatus uses a particular recording material and a contacting material. This particular recording material (hereinafter called recording material (A)) has a surface whose receding contact angle decreases when the surface is heated in a condition where the surface is in contact with a liquid or when the surface is in contact with a liquid in a condition where the surface is heated. The term "contact angle" refers to the angle by a vector which is tangent to a liquid which is in contact with a solid. The "receding contact angle", which is well known to those of ordinary skill in the art, is a measure of the wetting phenomena and is determined by slowly decreasing the size of the liquid until the drop of liquid recedes. The contacting material (hereinafter called contacting material (B)) is a liquid, a vapor or a material which liquidizes or generates a vapor at a temperature below the temperature at which the above mentioned receding contact angle begins to decrease. A latent image corresponding to the receding contact angle determined by controlling the temperature is formed on the surface of the recording material (A) by selectively heating the surface of the recording material (A) in a condition where the surface of the recording material (A) is contact with the contacting material (B) or by causing the surface of the recording material (A) to come in contact with the contacting material (B) after selectively heating the surface of the recording material (A). The latent image is made visual by a recording agent including a coloring agent, and then the visual image is transferred to a recording paper.
When printing a color picture by using the above mentioned recording method, for example as shown in FIG. 1, three single-color recording units are arranged in series. Each color of the three color is transferred to a sheet of paper by a respective one of the three recording units. Each of the recording units A, B, C of the apparatus shown in FIG. 1 comprises a latent-image forming device 1, an ink applicator 2, a recording material 3, transfer roller 5, a cleaner 6 and an erasing heater 7. The recording paper 4 passes, in turn, through a portion between each recording material and the respective transfer roller 5. Different color inks 2a, 2b, 2c are provided in corresponding ink applicators 2. This apparatus has a problem in that dots of each color tend to have displacement, that is, an undesired displacement between the center of each dot image so that the printed images are not appropriately superimposed, as recording units for each color are separated from each other. Thus, a high quality multi-colored picture cannot be obtained. Further, with this apparatus, the size of the apparatus becomes large and the manufacturing cost is increased.